This invention relates generally to systems for changing the pitch of all blades of a gyroplane rotary wing aircraft simultaneously and collectively to provide both for jump take-offs and for collectively controlling and adjusting the pitch of the blades while the aircraft is in flight.
The ability to simultaneously adjust or change the pitch of all rotor blades of a rotary wing aircraft is known as collective pitch control. Collective pitch control permits the blades of the aircraft to be pitched optimally during different phases of a flight. The blades can be depitched or set at a low angle of attack to reduce air resistance for cruising during forward flight, for example, or set at a higher angle for landing. The ability to control the pitch of the blades, both collectively (simultaneously for all blades) and cyclically (where the pitch of each blade changes as the blade rotates) is a necessary feature of helicopter design, and is also desirable in gyroplane rotary wing aircraft. Gyroplanes, known historically as autogyros, are a class of rotary wing aircraft in which the rotary wings or blades are rotated by air currents, not by engine torque. As a gyroplane moves through the air, air currents cause the rotor to turn by a process called autorotation. Although certain articulations of the blades, well known to those skilled in the art, are required to successfully operate gyroplanes, collective pitch control is optional. Both in the earliest autogyros and the newer generations of lightweight gyroplanes, fixed-pitch blades have often been used, usually to save weight, cost and complexity. Collective pitch control is desirable, however, since it permits jump take-offs and allows drag to be reduced in flight. Collective pitch control also provides greater control on landing. It would therefore be advantageous to have an improved collective pitch control system for gyroplane rotary wing aircraft which is simple to operate and effective.